Implement generalised list comprehensions

[ghc-hetmet.git] / compiler / typecheck / TcHsSyn.lhs

diff --git a/compiler/typecheck/TcHsSyn.lhs b/compiler/typecheck/TcHsSyn.lhs
index b9a2188..ff5c942 100644 (file)
--- a/compiler/typecheck/TcHsSyn.lhs
+++ b/compiler/typecheck/TcHsSyn.lhs
@@ -647,6 +647,37 @@ zonkStmt env (ExprStmt expr then_op ty)
     zonkTcTypeToType env ty    `thenM` \ new_ty ->
     returnM (env, ExprStmt new_expr new_then new_ty)
 
+zonkStmt env (TransformStmt (stmts, binders) usingExpr maybeByExpr)
+  = do { (env', stmts') <- zonkStmts env stmts 
+    ; let binders' = zonkIdOccs env' binders
+    ; usingExpr' <- zonkLExpr env' usingExpr
+    ; maybeByExpr' <- zonkMaybeLExpr env' maybeByExpr
+    ; return (env', TransformStmt (stmts', binders') usingExpr' maybeByExpr') }
+    
+zonkStmt env (GroupStmt (stmts, binderMap) groupByClause)
+  = do { (env', stmts') <- zonkStmts env stmts 
+    ; binderMap' <- mappM (zonkBinderMapEntry env') binderMap
+    ; groupByClause' <- 
+        case groupByClause of
+            GroupByNothing usingExpr -> (zonkLExpr env' usingExpr) >>= (return . GroupByNothing)
+            GroupBySomething eitherUsingExpr byExpr -> do
+                eitherUsingExpr' <- mapEitherM (zonkLExpr env') (zonkExpr env') eitherUsingExpr
+                byExpr' <- zonkLExpr env' byExpr
+                return $ GroupBySomething eitherUsingExpr' byExpr'
+                
+    ; let env'' = extendZonkEnv env' (map snd binderMap')
+    ; return (env'', GroupStmt (stmts', binderMap') groupByClause') }
+  where
+    mapEitherM f g x = do
+      case x of
+        Left a -> f a >>= (return . Left)
+        Right b -> g b >>= (return . Right)
+  
+    zonkBinderMapEntry env (oldBinder, newBinder) = do 
+        let oldBinder' = zonkIdOcc env oldBinder
+        newBinder' <- zonkIdBndr env newBinder
+        return (oldBinder', newBinder') 
+
 zonkStmt env (LetStmt binds)
   = zonkLocalBinds env binds   `thenM` \ (env1, new_binds) ->
     returnM (env1, LetStmt new_binds)
@@ -658,6 +689,9 @@ zonkStmt env (BindStmt pat expr bind_op fail_op)
        ; new_fail <- zonkExpr env fail_op
        ; return (env1, BindStmt new_pat new_expr new_bind new_fail) }
 
+zonkMaybeLExpr env Nothing = return Nothing
+zonkMaybeLExpr env (Just e) = (zonkLExpr env e) >>= (return . Just)
+
 
 -------------------------------------------------------------------------
 zonkRecFields :: ZonkEnv -> HsRecordBinds TcId -> TcM (HsRecordBinds TcId)